Lining plate for bank vaults and similar structures



urn LU) Feb. 5 1 924.

1,482,480 H. w. MOWERY LINING PLATE FOR BANK VAULTS AND SIMILARSTRUCTURES Filed May 19. 1922 V INVENTOR I A TTORNE y Patented Feb. 5,1924.

UNITED STATES PATENT OFFICE.

HAROLD WEAVER MOWERY, OF MAHWAH, NEW JERSEY, ASSIGNOR TO AMERICANABRASIVE METALS COMPANY, A CORPORATION OF NEW YORK.

LINING PLATE FOR BANK VAULTS AND SIMILAR STRUCTURES.

Application filed May 19, 1922. Serial No. 562,225.

To all whom it may concern:

Be it known that I, HAROLD WEAVER MOWERY, a citizen of the United Statesof America, residing at Mahwah, in the county of Bergen and State of NewJersey, have invented certain new and useful Improvements in LiningPlates for Bank Vaults and Similar Structures, of which the following isa specification.

My invention relates to linings or other portions of the walls of bankvaults, safes and other structures in which great powers of resistanceto the attacks of thieves and burglars are required. In the modern artof safe-cracking and bank robbing the use of electric drills, cuttingtorches and ex plosives has been brought to a high state of developmentand an equal degree of ingenuity is required to foil these attacks andprotect the contents of the safes and vaults.

I have discovered that an important factor in the problem is thestrength of the plate as a whole, as Well as the high melting point andgreat hardness which give it its power of resistance to drills andcutting torches. The particular function of strength is exerted inextending the effect of any explosions sufiiciently to bring down alarge quantity of dbris consisting of large masses of vault and buildingwalls which may itself form a barrier to further progress insurmountablein the limited time available to the burglar. Such increased strengthalso tends to increase the noise of the explosion, which, of course,acts as an alarm.

To this end my invention relates more specifically to improving thecharacter of the cast metal matrix in which masses of higher refractorycharacter have heretofore been embedded according to the previouspatents to Ralph S. Edmondson, No. 1,423,- 652, granted July 25, 1922,and Francis J. Napolitan, Nos. 1,422,295, granted July 11, 1922, and1,464,102, granted August 7, 1923. My invention has also increased theresistance to drills and cutting torches of such plate matrices. Itcomprises the employment of a ferrochrome alloy for the matrix, in placeof ordinary cast iron heretofore used.

I have discovered that such an alloy of 7% chromium and 93% iron givesthe best results. A higher percentage of chromium increases thehardness, but decreases the strength. While 7% of chromium gives thebest results, variations between limits of from 5% to 10% of chromiumcontent might be permissible in certain cases.

This alloy fulfills all the requirements which must be met to furnish apractical solution of the problem. It has great strength. A cylindricaltest bar 11,} inches in diameter placed on supports 12 inches apart willsupport a load of over 3500 lbs. applied midway between the supports.Its hardness is above that represented by 6 on the Brinnel hardnessscale, which is far above the point now considered sufiicient to rendera substance practically drill-proof. It has a relatively high meltingpoint and, if melted, solidifies at a slight reduction of temperature,so that it then forms masses which serve to partly clog up the hole thecutting torch is trying to bore. At the same time its melting point isnot so high that it is impracticable to cast it, and the cost is notprohibitive.

This is the only material, out of many I have tested, which possessesall the conflicting qualities above described to a sufliciently highdegree to satisfactorily resist drills, cutting torches and explosives.

The best form of structure at present known to me embodying my inventionis illustrated in the accompanying figure of drawing which shows across-section of the preferred form of plate, and in which 1 representsthe matrix or body of a plate formed of my ferro-chrome alloy, and 2, 2,represent irregular masses of still more refractory, but more brittle,metallic oxides embedded in the stronger matrix 1.

In some cases it might be possible to dispense with the masses 2, 2, andrely on the powers of resistance to drill and cutting torch of a solidplate made of the ferrochrome alloy 1.

Having described my invention, I claim:

1. A plate for use in constructing the walls of bank vaults and similarstructures composed of masses of refractory metallic oxides cast in aferro-chrome matrix.

2. A plate for use in constructing the walls of bank vaults and similarstructures composed of masses of refractory metallic oxides cast in aferro-chrome matrix containing approximately 7% of chromium.

HAROLD WEAVER MOWERY.

